See U.S. Pat. No. 4,227,584; 4,143,722 and their cited references.
The field of invention relates to downhole fluid or electrical motors used to drill vertical well holes, horizontal drain holes from vertical well holes and high angle directional wells.
Present directional drilling systems when only using regular drill pipe for drilling of horizontal holes or high angle holes from a vertical well can only deviate from the vertical a few degrees per hundred feet and to drill a curved hole from the vertical to the horizontal requires the radius of the curved hole to be several hundred feet. The use of downhole motors has reduced the radius of bend of the curved hole from the vertical to the horizontal but they are not as effective as they should be because of their long length The long length of the downhole motors restricts their use around curved holes with small radius of bend. So a downhole flexible drive system is need to operate around ultra short radiuses of bend.
It is an objective of the invention to provide improvements to downhole flexible drive system, particularly to the downhole flexible drive systems indicated in the cross reference to related application above.
It is an objective of the invention to provide a downhole flexible drive system which can be attached to the downhole end of a drill pipe string and operate a drill bit to drill a curved hole with an ultra short radius of bend.
It is an objective of the invention to provide a downhole flexible drive system powered by an assembly of short fluid double shaft motors.
It is an objective of the invention for the assembly of doubled shaft motors be assemble in line end to end and interfaced with a flexible shaft connecting to the shaft of the double shaft motors and a flexible tube connecting the ends of the flexible motors.
It is an objective of the invention to provide a double shaft pump in the drive train of the downhole flexible drive system to insure fluid flow through and over the face of a drill bit.
It is an objective of the invention to provide a means for the drive train of the downhole flexible drive system to carry part or all the tension loads on the system.
It is an objective of the invention to provide a means for some of the fluid driving the double shaft motor to be exhausted and directed back up the well hole with out going through the drill bit.